Arc-hive-omeka-theme/asset/js/expand-site-list-item.js

$(function(){
  $("#site-list").on( "click", ".accordion-title", function() {
    var title = this
    var content = $(this).closest('.accordion-item')
                         .find('.accordion-content')
    if ($(content).is(':visible')) {
      $(content).slideUp('fast')
      $(this).closest('.accordion-item').removeClass('is-active')
      $(title).attr('aria-expanded', false)
    } else {
      $(content).slideDown('fast')
      $(this).closest('.accordion-item').addClass('is-active')
      $(title).attr('aria-expanded', true)
    }
    return false;
  });
})